PROJECT SUMMARY/ABSTRACT This renewal application from the American Academy of Child and Adolescent Psychiatry (AACAP) requests support for the continuation of the AACAP Physician Scientist Program in Substance Use. Most mental and substance use disorders emerge during childhood and adolescence, but they are rarely recognized or addressed until adulthood. With specialized training in developmental psychopathology, child and adolescent psychiatrists are ideally suited to address these disorders before adulthood to reduce associated morbidity and mortality. While it is clearly recognized that substance use complicates the course of mental disorders, few child and adolescent psychiatrists receive specialized training to address substance use disorders, and exceedingly few pursue careers in research to advance substance use disorder prevention and treatment. Established in 1998, the AACAP Physician Scientist Program in Substance Use addresses this critical shortage by delivering a highly structured clinical research training and career development program for outstanding child and adolescent psychiatrists with the potential to make significant impacts on adolescent substance use disorder prevention and treatment. Since its inception, the program has successfully cultivated the careers of 24 child and adolescent psychiatrist physician-scientists. Twenty-three of the 24 scholars have gone on to establish or are well on their way to establishing careers in substance use-related research. AACAP remains an ideal institutional home for the K12 given its strong institutional commitment, ample resources, and membership that includes more than 95% of child and adolescent psychiatrists in the country, including all current and former K12 scholars. AACAP has pledged its continued commitment and support of scholars? career development if the renewal is awarded. Additionally, K12 scholars? research presentations at the AACAP Annual Meetings facilitate and accelerate the pace of translation from research to practice, clearly impacting the field. The program is making important progress, but more work is needed, as fewer than 2% of child and adolescent psychiatrists are significantly involved in research, and even fewer have established careers in substance use-related research. This renewal application proposes to build upon the program?s success to date by addressing the following aims. Aim 1: To increase the number of independently funded child and adolescent psychiatrist addiction researchers. Aim 2: To expand the network of senior mentors, academic centers, and addiction research training opportunities for K12 scholars and other early career investigators.